Fix some sign comparison warnings.

fpdfsdk/src/fpdfdoc_embeddertest.cpp

 // Copyright 2015 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "../../public/fpdf_doc.h"
 #include "../../public/fpdfview.h"
 #include "../../testing/embedder_test.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 class FPDFDocEmbeddertest : public EmbedderTest {};
 
 TEST_F(FPDFDocEmbeddertest, DestGetPageIndex) {
   EXPECT_TRUE(OpenDocument("testing/resources/named_dests.pdf"));
 
   // NULL FPDF_DEST case.
-  EXPECT_EQ(0, FPDFDest_GetPageIndex(document(), nullptr));
+  EXPECT_EQ(0U, FPDFDest_GetPageIndex(document(), nullptr));
 
   // Page number directly in item from Dests NameTree.
   FPDF_DEST dest = FPDF_GetNamedDestByName(document(), "First");
   EXPECT_NE(nullptr, dest);
-  EXPECT_EQ(1, FPDFDest_GetPageIndex(document(), dest));
+  EXPECT_EQ(1U, FPDFDest_GetPageIndex(document(), dest));
 
   // Page number via object reference in item from Dests NameTree.
   dest = FPDF_GetNamedDestByName(document(), "Next");
   EXPECT_NE(nullptr, dest);
-  EXPECT_EQ(1, FPDFDest_GetPageIndex(document(), dest));
+  EXPECT_EQ(1U, FPDFDest_GetPageIndex(document(), dest));
 
   // Page number directly in item from Dests dictionary.
   dest = FPDF_GetNamedDestByName(document(), "FirstAlternate");
   EXPECT_NE(nullptr, dest);
-  EXPECT_EQ(11, FPDFDest_GetPageIndex(document(), dest));
+  EXPECT_EQ(11U, FPDFDest_GetPageIndex(document(), dest));
 
   // Invalid object reference in item from Dests NameTree.
   dest = FPDF_GetNamedDestByName(document(), "LastAlternate");
   EXPECT_NE(nullptr, dest);
-  EXPECT_EQ(0, FPDFDest_GetPageIndex(document(), dest));
+  EXPECT_EQ(0U, FPDFDest_GetPageIndex(document(), dest));
 }